From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeroen Hofstee Date: Mon, 11 Aug 2014 19:51:16 +0200 Subject: [U-Boot] [PATCH 1/3] config: introduce a generic $bootcmd In-Reply-To: <53E8F50A.1060606@wwwdotorg.org> References: <1406759836-556-1-git-send-email-swarren@wwwdotorg.org> <53E25145.2090706@wwwdotorg.org> <53E4F400.6060508@wwwdotorg.org> <53E63816.60703@redhat.com> <53E6A3FE.6080807@myspectrum.nl> <53E6E2D0.7090303@wwwdotorg.org> <53E7A3A2.80707@myspectrum.nl> <53E8F50A.1060606@wwwdotorg.org> Message-ID: <53E90294.7060604@myspectrum.nl> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hello Stephan On 11-08-14 18:53, Stephen Warren wrote: > On 08/10/2014 10:53 AM, Jeroen Hofstee wrote: >> Hello Stephan, >> >> On 10-08-14 05:11, Stephen Warren wrote: >>> The entire point of this series is to prevent distros from having to >>> install bootloader-specific boot configuration files. > > >> I fail to see why this is something to pursue. Since the distro knows >> the boot path, why should u-boot be polling all possible options? > > This patch series allows U-Boot to find the OS and boot it. U-Boot is > searching for some kind of boot configuration file. > > This part of the process is the same as the BIOS searching all known > possible boot devices for a partition marked bootable, and with a > valid MBR. Or, it's the same as UEFI searching all possible boot > devices for whatever config file or boot binary is mandated by UEFI. > Not in my mind, I am not against scanning the possible boot devices, on the contrary, I am trying to add booting the userland from usb instead of mmc for the rpi_b. The part I dislike is where it starts searching for specific files. The equivalent would be your BIOS actively searching for GRUB, LILO, Windows Boot manager etc. etc. and as a fallback try the MBR. Also in this case the downstream provides information back, albeit tiny, it does indicate if it is bootable and a label to explain what is bootable. > U-Boot performs this searching before having any knowledge of the OS; > there's no way for the OS to parameterize this search path, just like > OSs don't configure a PC BIOS to search a specific HDD/floppy/CDROM > for the MBR to boot. > Yup as said, this is the part I was looking for. > Once U-Boot locates extlinux.conf or boot.scr, that file encodes what > files (kernel, DTB, initrd) This is the part I get for free now with it, I don't really like it, since if we take this road it ends up looking for e.g. grub.conf, ubldr.conf, vxworks.conf etc etc. I will have a look if I can tame the script, without modifying it nor u-boot, but I guess that is not possible since boot.scr comes after extlinux not before. Regards, Jeroen